Because the expense of providing operator services in communication systems is high, continuing efforts are being made to provide such services more efficiently. Modern systems use a program controlled processor for automatically performing many of the functions required for customer-dialed operator assistance calls. Such operator assistance systems connect the operator with the customer only when operator assistance is needed, i.e., when an operator assistance request is recognized in the system. At such times, an attended (active) operator position is connected to a customer, or bridged to a call connection which may already be set up, and is disconnected when service of the operator assistance request has been completed. The operator assistance system accumulates information concerning a call and displays that information at an operator position. Using this information about the current state of a call, an attending operator communicates verbally with the customer and keys additional call control and call record data into a terminal at the operator position. This data is sent to the control processor of the operator assistance system which then controls additional call configuration change functions, such as call connection and disconnection, and records billing and other data about the call.
Modern operator assistance systems usually serve calls from other end offices (telephone central offices connected to customers). Some also serve calls from customers connected directly to the system by customer lines. It is well known in the art that the cost of the transmission facilities, usually called trunks, for interconnecting end offices and operator assistance systems tends to be lower when the size of the geographic area supported by one operator assistance system is relatively small since transmission facility mileage requirements will be lower; this factor tends to favor the use of a large number of smaller operator assistance systems. However, it is also well known in the art that large groups of operators serve operator assistance requests more efficiently than small groups; this factor tends to favor the use of a small number of large operator assistance systems. In practice, a trade-off is usually made in the direction of a small number of large operator assistance systems. Therefore, a problem of the prior art is that more expensive voice transmission facilities are required.
Operator assistance traffic is much lower at night, especially after midnight. Even large operator assistance systems usually have small, hence less efficient, teams of operators on duty during such night hours. A problem of the prior art systems is that the night operator assistance traffic from multiple geographic regions cannot be funneled into a centralized operator assistance system, but must continue to be served from the same operator assistance system which handles the daytime traffic from that region. While some older operator systems, such as automatic call distributors used for incoming calls to large businesses, offer the night transfer feature, this feature is usually implemented by simply reswitching calls to another location; such an arrangement cannot support systems in which the operator controls the configuration and billing of a call.
It has been recognized by those in the telecommunication art that it would be economically advantageous to serve operator assistance calls in a system which is too small to justify the presence of a team of operators even during normal business hours; to handle such a situation efficiently, operator assistance requests on calls in such a system must be served by operators from another system. Small operator assistance systems and larger systems carrying only a small amount of operator assistance traffic are likely to be more prevalent as modern systems which are economical at small sizes are provided with operator assistance features. A problem in the prior art is that no arrangements are available to permit an operator in one operator assistance system to serve an operator assistance request from the call of another operator assistance system.
These problems of the prior art are all manifestations of a common limitation of prior art systems: operator assistance traffic from a given geographic area is served by operators associated with a given operator assistance system. This limitation is brought about by restrictions on the kinds of signals which may be passed through the public switched network and the characteristics of the data necessary to support an operator assistance request, much of which is only available in the operator assistance system connected to the calling customer. Part of this data pertains to the particular call and is accumulated during the course of the call. Another part, for example, for calculating coin call charges, is specific to the particular geographic area served by an operator assistance systems. Signaling messages and other data for identifying the directory number and geographic location of a customer originating an operator assistance call are available only in the single operator assistance system serving the geographic area of that customer. Since some calls generate more than one operator assistance request, each request usually served by a different operator, the data for notifying an operator of what has transpired on a given call must be available to any operator serving that call. All of these factors indicate that a complete data base can be readily provided only at the operator assistance system which initially receives a call.
In summary, a need exists for a system to allow operators associated with one operator assistance system to selectively serve operator assistance requests for calls directed to another operator assistance system, and the need has not been met in the prior art because of the limitations imposed by the need for data derived from a data base and incoming and outgoing signaling tied to the latter system.